Microtubules are hollow polymers made up of tubulin subunits. Neurons, like other eukaryotic cells, contain a pool of free tubulin subunits and a pool of the microtubule polymers. These two pools dynamically exchange with one another such that microtubules undergo bouts of assembly and disassembly.n neurons, microtubules are also nucleated at the centrosome (located in the cell body of the neuron), but the microtubules are then severed from the centrosome so that they can be deployed into axons and dendrites.
If the parent makes this election, the child does not have to file a return. Earned and Unearned Income. If a child has both earned and unearned income, he or she must file a return (2016 and 2015) if: unearned income was over $1,050; earned income was over $6,300, or
Once your income reaches a certain threshold, you have to file a federal income-tax return. The income limits depend on your filing status -- single, married, widowed or head of household -- and your age.If youâre 65 or older, the threshold for filing your taxes is higher.f you are married filing separately, you must file a tax return if your income is $3,650 or more, regardless of your age. Dependent children who worked for wages or tips or who collected income from investments in 2009 must file a tax return if: -- their earned income from a job was at least $5,700.